Comment to the paper "Re-evaluation of activities of magnesium and zinc components in the magnesium-zinc binary system from very low to high temperature"

In the paper "Re-evaluation of activities of magnesium and zinc components in the magnesium-zinc binary system from very low to high temperature" by Morishita et al. [1] which recently appeared as a Feature Article in this journal, the authors made the following three statements, commencing with the first sentence of the abstract: 1. "The activities of zinc, a(Zn) and magnesium, a(Mg) from very low to high temperatures in the Mg-Zn binary system were evaluated for the first time from the relationship between the Gibbs energies of formation, Delta(f)G(T)(o), of Mg48Zn52, Mg2Zn3, MgZn2 and Mg2Zn11 and their phase equilibria." 2. "It was found that the a(Zn) and a(Mg) values in the compounds steeply changed from the minimum to maximum as a function of the composition in a narrow solubility range." 3. " ... at very low temperatures, a(Zn) and a(Mg) were very small approaching to zero, ... "; "The values of log a(Zn) and log a(Mg) in the two-phase regions were found to be decreased ... and resulted in very small values". These three statements are disputed and commented below. For convenience, let us start with the second statement.